phi

The word “phi” means the 21st letter of the Greek alphabet (Φ, φ), often used as a symbol in science and mathematics. In plain terms, a Greek letter, commonly used as shorthand for the golden ratio in math and design.

“Phi” is pronounced feye (/faɪ/ in IPA).

Here is “phi” used in a sentence: “In the equation, phi represents the phase angle.”

“Phi” is a noun.

The word “phi” comes from Latin. From the Greek letter phei, borrowed into Latin and then English as "phi.".

“Phi” is an uncommon word in modern English.

“Phi” has 2 distinct senses listed in this dictionary. The most common is: the 21st letter of the Greek alphabet (Φ, φ), often used as a symbol in science and mathematics.

Phi (Φ, φ) and pi (Π, π) are both letters of the Greek alphabet used as mathematical symbols, but they represent different constants: phi commonly denotes the golden ratio, approximately 1.618, while pi denotes the ratio of a circle's circumference to its diameter, approximately 3.14159. They are unrelated numbers that simply share Greek origin.

Phi is used as a symbol across many fields of science and mathematics, most notably to represent the golden ratio, approximately 1.618, a number linked to certain proportions found in geometry, art, and nature. It also appears in physics and statistics to denote other specific quantities depending on context.

Phi is the 21st letter of the Greek alphabet, written as Φ in its uppercase form and φ in its lowercase form. It comes after chi and before khi in some traditional orderings, though modern Greek places it among the later letters of the alphabet.